//
//  UIImage+fieOrientation.m
//  猫狗交流器
//
//  Created by apple on 2018/9/7.
//  Copyright © 2018年 mac. All rights reserved.
//

#import "UIImage+fieOrientation.h"

@implementation UIImage (fieOrientation)
+ (UIImage *)fixOrientation:(UIImage *)aImage {
    
    
    
    // No-op if the orientation is already correct
    
    if (aImage.imageOrientation ==UIImageOrientationUp)
        
        return aImage;
    
    
    
    // We need to calculate the proper transformation to make the image upright.
    
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    
    CGAffineTransform transform =CGAffineTransformIdentity;
    
    
    
    switch (aImage.imageOrientation) {
            
        case UIImageOrientationDown:
            
        case UIImageOrientationDownMirrored:
            
            transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);
            
            transform = CGAffineTransformRotate(transform, M_PI);
            
            break;
            
            
            
        case UIImageOrientationLeft:
            
        case UIImageOrientationLeftMirrored:
            
            transform = CGAffineTransformTranslate(transform, aImage.size.width,0);
            
            transform = CGAffineTransformRotate(transform, M_PI_2);
            
            break;
            
            
            
        case UIImageOrientationRight:
            
        case UIImageOrientationRightMirrored:
            
            transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);
            
            transform = CGAffineTransformRotate(transform, -M_PI_2);
            
            break;
            
        default:
            
            break;
            
    }
    
    
    
    switch (aImage.imageOrientation) {
            
        case UIImageOrientationUpMirrored:
            
        case UIImageOrientationDownMirrored:
            
            transform = CGAffineTransformTranslate(transform, aImage.size.width,0);
            
            transform = CGAffineTransformScale(transform, -1, 1);
            
            break;
            
            
            
        case UIImageOrientationLeftMirrored:
            
        case UIImageOrientationRightMirrored:
            
            transform = CGAffineTransformTranslate(transform, aImage.size.height,0);
            
            transform = CGAffineTransformScale(transform, -1, 1);
            
            break;
            
        default:
            
            break;
            
    }
    
    
    
    // Now we draw the underlying CGImage into a new context, applying the transform
    
    // calculated above.
    
    CGContextRef ctx =CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,
                                            
                                            CGImageGetBitsPerComponent(aImage.CGImage),0,
                                            
                                            CGImageGetColorSpace(aImage.CGImage),
                                            
                                            CGImageGetBitmapInfo(aImage.CGImage));
    
    CGContextConcatCTM(ctx, transform);
    
    switch (aImage.imageOrientation) {
            
        case UIImageOrientationLeft:
            
        case UIImageOrientationLeftMirrored:
            
        case UIImageOrientationRight:
            
        case UIImageOrientationRightMirrored:
            
            // Grr...
            
            CGContextDrawImage(ctx,CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);
            
            break;
            
            
            
        default:
            
            CGContextDrawImage(ctx,CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.CGImage);
            
            break;
            
    }
    
    
    
    // And now we just create a new UIImage from the drawing context
    
    CGImageRef cgimg =CGBitmapContextCreateImage(ctx);
    
    UIImage *img = [UIImage imageWithCGImage:cgimg];
    
    CGContextRelease(ctx);
    
    CGImageRelease(cgimg);
    
    return img;
    
}
@end
